Rock sampling difficulties
Rock sampling difficulties
(OP)
Hi
It happened to me in the past and it may happen for my incoming projects , we had many problems drilling in a rock that caused our core drilling and bits to be damaged . What are the criteria to be respected for the choice of the drilling tools ? if i am right i believe it has to do with the chemical constituents mainly carbon and Tungsten ?
It happened to me in the past and it may happen for my incoming projects , we had many problems drilling in a rock that caused our core drilling and bits to be damaged . What are the criteria to be respected for the choice of the drilling tools ? if i am right i believe it has to do with the chemical constituents mainly carbon and Tungsten ?





RE: Rock sampling difficulties
RE: Rock sampling difficulties
In no particular order there are three main items that affect rock coring:
1. Cutting material. As you pointed out different material is used for the cutting teeth on core bits including carbide and diamond. Generally any material will cut softer rock, but harder rock generally requires diamond bits.
2. Size of the cutting teeth. In general larger teeth are used to cut softer rock such as most shales since that helps prevent the bit from becoming blocked off. However, if harder rock is encountered the larger teeth can be sheared off.
3. Type of drilling fluid. Usually, water or a bentonite/water mixture is fine for rock coring. When coring rock that tends to swell on contact with water, a polymer drilling fluid is often used to reduce the amount of swell.
Other items such as rotational speed of the bit, size of the equipment, water flow, and down pressure can also dramatically affect coring. In the end, it all comes down to have a good drill company and drill operator.
Mike Lambert
RE: Rock sampling difficulties
GeoPavTraffic you are right advice n°2 is very interesting . Does diamond bits with deep chiseled carvings fair better than flat bits with diamond powder ?
RE: Rock sampling difficulties
Mike Lambert
RE: Rock sampling difficulties
RE: Rock sampling difficulties
These variations are based on the fact that these distinctions affect the drilling rate. In a very hard rock, you may want a softer matrix. That way, the matrix gets out of the way to reveal more of the diamond surfaces. In a soft rock you may want a harder matrix to control bit wear.
I never quite knew when to use impregnated versus set diamond bits. Then again, impregnated bits are less expensive!
Lots has changed since I spent countless hours logging rock core.
f-d
ípapß gordo ainÆt no madre flaca!
RE: Rock sampling difficulties
RE: Rock sampling difficulties
https://www.ybm.jp/Product/Tools/sharkbit.htm
I did not know that they come from North America:
http://www.fordia.com/types-produits/core-bits/
With just water as drilling mud,these bits have been performing well for us.
RE: Rock sampling difficulties